Hypodermic needle assemblies are commonly used to administer drugs or other medicinal substances, whether in a hospital or clinic or at home. Sometimes the hypodermic needle assembly is prepared ahead of time and stored in a cabinet or refrigerator until use. For example, a medical practitioner (e.g., a nurse) may have instructions for administering a certain medicine hypodermically to a certain patient. The medical practitioner may inadvertently take the incorrect needle assembly from the cabinet or refrigerator and administer the wrong medicine to that particular patient, with possibly serious repercussions. It would therefore be desirable to prevent unauthorized administration of a drug or medicinal substance from a hypodermic needle assembly and the like.